Key Laboratory of State Forestry and Grassland Administration on Forest Ecosystem Protection and Restoration of Poyang Lake Watershed, Jiangxi Agricultural University, Nanchang, 330045, China; Key Laboratory of Wetland Ecology and Environment, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun, 130102, China.
Key Laboratory of Wetland Ecology and Environment, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun, 130102, China; School of Environment, Nanjing Normal University, Nanjing, 210023, China.
Environ Pollut. 2020 May;260:114030. doi: 10.1016/j.envpol.2020.114030. Epub 2020 Jan 23.
Temperate wetlands have been undergoing increased nitrogen (N) inputs in the past decades, yet its influence on dissolved organic carbon (DOC) dynamics is still elusive in these ecosystems. Here, using a field multi-level N addition (0, 6, 12, and 24 g N m year) experiment, we investigated the changes in aboveground plant biomass, DOC production from plant litters, DOC biodegradation, and DOC concentration in surface water and soil pore water (0-15 cm depth) following 10 years of N addition in a freshwater marsh of Northeast China. We observed that, irrespective of N addition levels, N addition caused an increase in DOC production from plant litters under both non-flooded and flooded conditions. Conversely, DOC biodegradation was inhibited by N addition in both surface water and soil pore water. Because of enhanced DOC production from plant litters and declined DOC biodegradation, N addition elevated DOC concentration in surface water and soil pore water across the growing season. In addition, long-term N addition increased aboveground plant biomass, but decreased species richness. Our results suggest that long-term N enrichment promotes DOC accumulation through the contrasting effects on litter-derived DOC production and microbial decomposition of DOC in temperate wetlands.
过去几十年来，温带湿地的氮（N）输入不断增加，但它对溶解有机碳（DOC）动态的影响在这些生态系统中仍然难以捉摸。在这里，我们使用野外多层次 N 加（0、6、12 和 24 g N m year）实验，研究了 10 年 N 加后，中国东北淡水沼泽地上空植物生物量、植物凋落物产生的 DOC、DOC 生物降解以及地表水和土壤孔隙水（0-15 cm 深度）中 DOC 浓度的变化（0、6、12 和 24 g N m year）实验，研究了 10 年 N 加后，中国东北淡水沼泽地上空植物生物量、植物凋落物产生的 DOC、DOC 生物降解以及地表水和土壤孔隙水（0-15 cm 深度）中 DOC 浓度的变化（0、6、12 和 24 g N m year）实验，研究了 10 年 N 加后，中国东北淡水沼泽地上空植物生物量、植物凋落物产生的 DOC、DOC 生物降解以及地表水和土壤孔隙水（0-15 cm 深度）中 DOC 浓度的变化。无论 N 添加水平如何，N 添加都会在非淹没和淹没条件下增加植物凋落物产生的 DOC。相反，N 添加抑制了地表水和土壤孔隙水中的 DOC 生物降解。由于植物凋落物产生的 DOC 增加和微生物对 DOC 的生物降解减少，N 添加增加了整个生长季节地表水和土壤孔隙水中的 DOC 浓度。此外，长期 N 添加增加了地上植物生物量，但降低了物种丰富度。我们的结果表明，长期 N 富集通过对凋落物产生的 DOC 和微生物对 DOC 的分解的相反影响，促进了温带湿地中 DOC 的积累。
